JP2006142203A - Ink jet coater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet coater which reduces dispersion of an ink jetting direction and other ink jetting properties caused by an unsymmetrical profile and and a wetting property of an ink jet nozzle and forms a stable and proper membrane that has good impact accuracy and little dispersion of jetting properties, thereby providing little labor of maintenance. <P>SOLUTION: The ink jet coater is provided with an ink chamber 65 installed in the ink jet head 6, a nozzle plate 66 installed at the lower end part of the ink jet head, a nozzle 67 installed in the nozzle plate 66 communicating with the ink chamber 65, an actuator 62 to jet ink and a vibration source 11 that is installed in the nozzle 66 and gives vibration to the neighborhood of the nozzle 67. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet coating apparatus that applies ink by spraying ink onto a predetermined area of a substrate in the form of fine droplets.

  When manufacturing a display device using a thin display panel such as a semiconductor device, a liquid crystal display panel, an organic EL (electroluminescence) display panel, or a field emission display panel, an aqueous solution or a coating solution containing an inorganic or organic solvent is used. A film such as a functional layer is formed by spraying droplets onto a substrate from an inkjet nozzle of an inkjet coating apparatus and drying the droplets on the substrate. Such ink jet coating is particularly suitably used for film formation that requires fine patterning such as a light emitting layer and a color filter layer of a display device.

  An ink jet coating apparatus includes a micro nozzle on a nozzle plate provided at a lower end portion of an ink jet head, and ejects ink droplets from the nozzle toward a substrate which is a material to be coated, while the ink jet head and the substrate. By reciprocating one or both of the stages supporting the ink in a horizontal plane, the ink landed on the substrate is applied within a predetermined range of the substrate.

  An opening end portion of the nozzle provided in communication with an ink chamber inside the ink jet head is formed by performing precision processing such as laser processing or etching on a nozzle plate provided with the nozzle. However, even if the opening end portion of the nozzle is subjected to the precision processing, it is difficult to obtain a completely symmetric shape when viewed from the substrate to which the ink is applied. For this reason, the ink ejected from this nozzle is affected by the shape of the opening end of the nozzle and the wettability, and the ejection direction is biased in any direction, which may lead to a decrease in ink landing accuracy. there were.

  The inkjet head is generally provided with a plurality of nozzles according to the type of ink to be applied or in order to improve productivity. In this case, for each of the plurality of nozzles, the shape and wettability of the opening end of the nozzle are different for the reasons described above. Therefore, the ejection direction of ink ejected from these nozzles, the ejection speed of liquid droplets, and the liquid In some cases, the ejection characteristics such as the droplet amount and the ink shape vary.

  Therefore, conventionally, in order to obtain a desired constant ejection characteristic, it has been necessary to adjust ejection conditions for each nozzle for one or a plurality of nozzles provided in the inkjet. In addition, since the shape and wettability of the opening end of the nozzle changes with time, it is necessary to readjust the injection conditions periodically.

  When the ink landing accuracy is reduced or the ejection characteristics of each nozzle vary, the shape and thickness of the film formed by ejecting the ink droplets will vary, which causes the inkjet coating process to pass. This is not preferable because it directly leads to a defect in the manufactured product.

  In a manufacturing process of a display device in which a bank for receiving ink is provided on the surface of a glass substrate, such as a polymer organic EL display, and a light emitting layer is formed by ejecting ink into the bank by inkjet coating. When the aforementioned deviation in the injection direction and variation in the injection characteristics occur, the landing position and the injection amount on the substrate for one nozzle change, and the landing position and the injection amount on the substrate for each nozzle change. It becomes uneven. For this reason, variations occur in the shape of the light emitting layer after ink drying, which deteriorates the quality of the panel and decreases the yield. Moreover, the adjustment for eliminating the variation is complicated.

  In addition, when adjustment of the ejection conditions by the drive voltage, drive pulse width, drive frequency, etc. of the actuator for ejecting ink from the ink chamber of the inkjet head is inappropriate, the ink is pushed from the ink chamber to the nozzle opening end. When a portion of the ink other than the one that has been broken into droplets tries to return to the nozzle chamber, the nozzle opening instead of the nozzle chamber is affected by the shape and wettability of the nozzle opening end. May adhere to the nozzle plate around. In addition, there are cases in which minute droplets generated when ink is torn off adhere to the nozzle plate as well. The ink adhering to these nozzle plates overlaps each time the number of ejections in the ink jet coating process is repeated, and the area is enlarged to form a water pool near the nozzles. Ink adhering to such a pooled state hinders ink ejection and prevents stable ejection. For this reason, in order to perform stable injection, maintenance operations such as wiping off droplets on the nozzle plate must be frequently performed, and productivity is reduced.

  The present invention has been made in order to advantageously solve the above-described problems, and reduces the influence of the shape and wettability of the opening end of the nozzle, providing good landing accuracy and less variation in injection characteristics. Therefore, an object of the present invention is to provide an inkjet coating apparatus that can form a good film stably with less maintenance work.

  The inkjet coating apparatus of the present invention is provided in the inkjet head, and is provided in the nozzle plate in communication with the ink chamber, the nozzle chamber provided in the lower end portion of the inkjet head, and the ink chamber. A nozzle that opens toward the substrate to which ink is applied, an actuator that ejects ink contained in the ink chamber from the nozzle, and a nozzle plate that is provided close to the nozzle and vibrates in the vicinity of the opening. And a vibration source to be applied.

  In the ink jet coating apparatus of the present invention, the vibration source is preferably a combination of a comb electrode and a piezoelectric body.

  In the inkjet coating apparatus of the present invention, it is advantageous that a plurality of the nozzles are provided on the nozzle plate, and the vibration source is provided on each of these nozzles.

  Further, in the method of manufacturing a display device having a coating process in which ink is ejected toward the substrate surface using the inkjet coating apparatus of the present invention, the substrate surface while applying vibration to the nozzle by the vibration source in the coating process. By ejecting ink toward the surface, a display device having a good quality can be manufactured with a high yield.

  According to the present invention, it is possible to perform stable and favorable film formation with little variation in ejection characteristics.

  FIG. 1 is a perspective view showing an overall configuration of an inkjet coating apparatus according to an embodiment of the present invention. The ink jet coating apparatus of the present invention includes a base 1, and a stage 2 that holds a substrate S on which ink is applied is disposed substantially horizontally on the base 1. The stage 2 is supported so as to be movable in a horizontal plane by an X table 3a, a Y table 3b, and a θ table 3c sequentially provided from the upper surface of the base 1.

  A gate-shaped support 4 is erected substantially vertically from the upper surface of the base 1 so as to straddle the stage 2. An ink jet head driving device 5 is attached to the support 4 at a position directly above the stage 2. An inkjet head 6 is provided at the lower end of the inkjet head driving device 5.

  In order to supply ink to the ink jet head 6, a plurality of ink supply tanks 7 are provided, and are connected to the ink jet head 6 by pipes 8. In these ink supply tanks 7, for example, when a colored film of a color filter of a liquid crystal display panel or a light emitting film of an organic EL panel is formed by the ink jet coating apparatus, it corresponds to each of R, G, and B3 colors, respectively. Color ink is stored. An ink supply tank 7 is provided on the base 1 in order to maintain the ink liquid pressure at the nozzle tip of the inkjet head 6 at a predetermined negative pressure by appropriately adjusting the liquid level of the ink. It is supported by an ink supply tank drive mechanism that is not movable up and down.

  In order to supply ink when the amount of ink stored in the ink supply tank 7 is reduced, a plurality of ink supply tanks 9 corresponding to the ink supply tank 7 are provided, each connected to the ink supply tank 7 by a pipe 8. is doing.

  An ink application box 10a is provided to cover the above-described members provided on the base 1 and maintain a space for ink-jet application in a predetermined atmosphere. Adjacent to the ink application box 10a, there is an ink supply box 10b that holds the space near the ink supply tank 9 in a predetermined atmosphere in order to prevent the atmosphere in the ink application box 10a from fluctuating when ink is supplied. Is provided.

  FIG. 2 is an enlarged view of the vicinity of the inkjet head 6 of the inkjet coating apparatus shown in FIG.

  The inkjet head drive device 5 is attached to the Y table 5b, a Z table 5a attached to the support 4 so as to be movable up and down, a Y table 5b attached to the Z table so as to be movable in the horizontal direction, and the Y table 5b. The θ table 5c is rotatable about the vertical direction as a rotation axis, and the inkjet head 6 is provided at the lower end of the θ table 5c. A nozzle for ejecting ink droplets is attached to the lower end surface of the inkjet head 6 toward the stage 2.

  3 is a perspective view of the inkjet head 6 shown in FIG. 2, and FIG. 4 is a cross-sectional view taken along the line AA of the inkjet head 6 shown in FIG. 3 and 4, the inkjet head 6 includes a base 61 having a gap, an actuator 62 made of a piezoelectric element inserted in the gap of the base 61, a diaphragm 63 fixed to the tip of the actuator, The diaphragm 63 includes a flow path plate 64 attached to the surface of the diaphragm 63 opposite to the base 61, and a gap formed in the flow path plate 64 and filled with the ink i, and the actuator 62 is fixed. An ink chamber 65 having the diaphragm 63 as a part of the inner wall of the gap, a nozzle plate 66 attached to the end surface of the flow path plate 64 so as to close the ink chamber 65, and the nozzle plate 66. And a nozzle 67 that communicates with the ink chamber 65 and ejects ink.

  When a voltage is applied to the actuator 62 made of a piezoelectric element, the actuator 62 contracts to pull the diaphragm 63. Therefore, the diaphragm 63 is elastically deformed, and the volume of the ink chamber 65 having the diaphragm 63 as a part of the inner wall increases. The ink chamber 65 is connected to a pipe 8 connected to the ink supply tank 7 through a flow path (not shown), and the amount of ink filled in the ink chamber 65 increases.

  Next, when the application of voltage to the actuator 62 is stopped, the actuator 62 returns to its original length, and the elastic deformation of the diaphragm 63 also returns to its original state. Then, the volume of the ink chamber 65 having the diaphragm 63 as a part of the inner wall also returns, and the increment of the ink i filled in the ink chamber 65 is ejected as a droplet from the nozzle 67.

  When the ejection direction of the ink i ejected from the nozzle 67 is biased due to the shape of the opening end of the nozzle 67 provided on the nozzle plate 66 of the inkjet head 6 or the wettability. As described above, there is a problem that causes a drop in ink landing accuracy.

  Therefore, in the present embodiment, the vibration source 11 that applies vibration in the vicinity of the opening of the nozzle 67 is provided at the end in the width direction of the surface of the nozzle plate 66.

  FIG. 5 shows a view of the inkjet head 6 of this embodiment shown in FIG. 4 as viewed from the bottom. In FIG. 5, the position and dimensions of the members are different from those in FIG. 4 in order to facilitate the description of the vibration source 11.

  In FIG. 5, the vibration source 11 includes a piezoelectric body 11a fixed on a nozzle plate 66, and a comb-shaped electrode 11b provided on the piezoelectric body 11a. In the comb-shaped electrode 11b, a pair of electrodes having portions arranged in parallel at a predetermined interval are alternately combined in the portions arranged in parallel. Then, the combined arrangement of the parallel arranged portions is formed on the piezoelectric body 11 a so as to face the nozzle 67. The comb electrode 11b is connected to a power source 12.

  When an AC voltage is applied to the comb-shaped electrode 11b from the power source 12, the piezoelectric body 11a repeatedly deforms in accordance with the voltage change of the AC voltage due to the piezoelectric effect, and a frequency corresponding to the interval between the portions arranged in parallel. Surface acoustic waves (Rayleigh waves) having This surface acoustic wave is generated from the vibration source 11 provided at the end of the nozzle plate 66 in the direction of arrow W in the drawing, that is, the arrangement direction of the comb-shaped electrodes 11b arranged in parallel (direction toward the nozzle). Progress in parallel with

  Therefore, in the inkjet coating apparatus of this embodiment shown in FIG. 5, when a predetermined high-frequency AC voltage is applied from the power source 12 to the comb-shaped electrode 11b of the vibration source 11 by a signal from a control device (not shown), the vibration source 11 generates. The surface acoustic wave travels toward the nozzle 67, and vibration is applied to the opening end of the nozzle 67 and the vicinity thereof.

  FIG. 6 is a cross-sectional view of the vicinity of the nozzle 67 during ink application. As shown in the figure, when the ink i is ejected from the nozzle 67, vibration is applied to the opening end of the nozzle 67 by the surface acoustic wave W, so that the ink i and the opening end of the nozzle 67 are separated. The ink comes into contact intermittently rather than continuously, and the ink contact time at the opening end during ejection is shortened. Therefore, the influence of the shape of the opening end and the asymmetry of the wettability on the jetting characteristics is reduced. In addition, the influence of changes in the shape and wettability of the nozzle 67 over time is reduced, and the shape and wettability of the opening end due to foreign matter m present at the opening end shown in the drawing or nozzle processing failure, etc. The influence of is reduced.

  Even in the case where ink such as fine droplets adheres around the nozzle 67 on the nozzle plate 66, the surface acoustic wave W travels from the vibration source 11 toward the nozzle 67 in the present embodiment. Thus, the ink adhering to the periphery of the nozzle 67 moves to the end of the nozzle plate 66 along with the surface acoustic wave W. Therefore, since ink does not collect around the nozzle 67, a stable inkjet coating process can be performed. In this way, to prevent ink from collecting around the nozzle 67 on the nozzle plate 66, it is possible to prevent the solidified ink collected around the nozzle 67 from obstructing nozzle ejection as foreign matter. In this respect, it is possible to stably perform highly accurate ink jet coating.

  Further, when a minute droplet of ink adheres to the comb-shaped electrode 11b of the vibration source 11 shown in FIG. 5, the impedance when a predetermined AC voltage is applied to the comb-shaped electrode 11b to generate a surface acoustic wave changes. By utilizing this, the comb-shaped electrode 11b is provided in the vicinity of the opening of the nozzle 67, the impedance of the comb-shaped electrode 11b is monitored by a detection device (not shown), and a fine droplet is placed on the nozzle plate 66 around the nozzle 67 opening. Is detected by the change in the impedance of the comb-shaped electrode 11b, it can be predicted that the minute droplets overlap and a liquid pool is formed in the vicinity of the opening of the nozzle 67, resulting in non-ejection of ink. it can.

  In the present embodiment, the frequency of the surface acoustic wave generated from the vibration source 11 is usually about 0.1 to 0.2 μs during the time when the ink is in contact with the nozzle 67 in the inkjet coating. In order to obtain the effect, the frequency is preferably about 10 MHz to 1 GHz. Such frequency vibration can be generated by a combination of a comb-shaped electrode and a piezoelectric body.

  As shown in FIG. 5, when a plurality of nozzles 67 are provided on the nozzle plate 66, a plurality of vibration sources 11 are provided corresponding to each of these nozzles, whereby the ejection characteristics for each nozzle. Variation can be reduced, and troublesome adjustment can be reduced.

  A display device can be manufactured using the inkjet coating apparatus of the present invention. In the manufacturing process of a display device, there is a step of forming a light emitting element layer in the case of an organic EL panel or a colored layer or a black matrix layer in the case of a color filter of a liquid crystal panel on the substrate of the display device. Since it is necessary to form a layer in a finely divided region, the coating liquid is applied and dried by the ink jet coating apparatus of the present invention, and the light emitting film of the light emitting element or the colored film of the color filter or the light shielding. A film can be formed.

  More specifically, for example, in the case of manufacturing a liquid crystal display as a display device, a TFT array substrate in which thin film transistors (TFTs) are regularly arranged on a glass substrate is manufactured, and color filters and black are provided on another glass substrate. A color filter substrate on which a matrix is formed is manufactured, the TFT array substrate and the color filter substrate are bonded together and assembled, a liquid crystal material is injected into the gap between the bonded substrates, and sealed to obtain a panel substrate . In order to obtain a panel substrate, both a color filter and a black matrix are formed on the TFT array substrate.

  In manufacturing such a color filter substrate, or a TFT array substrate on which a color filter and a black matrix are formed, in order to form a colored layer corresponding to each bright spot (subpixel) of the color filter layer, or Using the inkjet coating apparatus of the present invention, a non-display area provided around the display area constituted by each bright spot or a film for forming a light shielding layer (black matrix) for shielding light between the bright spots is used. Can be formed.

  When a display device is manufactured using the inkjet coating apparatus of the present invention, a good film is stably formed by ejecting ink toward the substrate surface while vibrating the nozzle by the vibration source. be able to.

1 is a perspective view showing an overall configuration of an ink jet coating apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of the vicinity of an inkjet head 6 of the inkjet coating apparatus shown in FIG. 1. FIG. 3 is a perspective view of the inkjet head 6 shown in FIG. 2. FIG. 4 is an AA cross-sectional view of the inkjet head 6 shown in FIG. 3. The figure which looked at the inkjet head shown in FIG. 4 from the bottom face. Sectional drawing of nozzle 67 vicinity at the time of ink application | coating.

Explanation of symbols

6 ... Inkjet head, 11 ... Vibration source, 12 ... Power source, 62 ... Actuator, 65 ... Ink chamber, 66 ... Nozzle plate, 67 ... Nozzle

Claims (4)

An ink chamber provided in the inkjet head and containing ink;
A nozzle plate provided at the lower end of the inkjet head;
A nozzle provided in the nozzle plate in communication with the ink chamber and opening toward a substrate to which ink is applied;
An actuator for ejecting ink contained in the ink chamber from the nozzle;
A vibration source provided in the nozzle plate in the vicinity of the nozzle and applying vibration in the vicinity of the opening;
An inkjet coating apparatus comprising:   The ink jet coating apparatus according to claim 1, wherein the vibration source is a combination of a comb electrode and a piezoelectric body.   The inkjet coating apparatus according to claim 1, wherein a plurality of the nozzles are provided on the nozzle plate, and the vibration source is provided on each of the nozzles. In the manufacturing method of the display device which has the application process which spouts ink toward the substrate surface using the ink jet application device according to any one of claims 1 to 3.
A method of manufacturing a display device, wherein, in the application step, ink is ejected toward a substrate surface while applying vibration to the nozzle by the vibration source.

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